Table of Contents: October 2009

Each colony has thousands of female workers, one queen, and a few hundred males (drones). This strong sex bias relies on an unusual sex determination system. Gempe et al. (e1000222) show key functions for the regulation of two genes: csd, which establishes the decision between males and females by allelic combination, and fem, which memorizes the sexual decision by a positive regulatory feedback loop that operates throughout development.